Apparatus for caries detection

Abstract

An apparatus for obtaining an image of a tooth having at least one light source providing incident light having a first spectral range for obtaining a reflectance image ( 122 ) from the tooth and a second spectral range for exciting a fluorescence image ( 120 ) from the tooth. A polarizing beamsplitter ( 18 ) in the path of the incident light from both sources directs light having a first polarization state toward the tooth and directs light from the tooth having a second polarization state along a return path toward a sensor ( 68 ), wherein the second polarization state is orthogonal to the first polarization state. A first lens ( 22 ) in the return path directs image-bearing light from the tooth toward the sensor ( 68 ), and obtains image data from the portion of the light having the second polarization state. A long-pass filter ( 15 ) in the return path attenuates light in the second spectral range.

1. An apparatus for imaging a tooth comprising:
 (a) at least one light source providing incident light having a first spectral range for obtaining a reflectance image on the tooth and a second spectral range for exciting a fluorescence image of the tooth; 
 (b) a polarizing beamsplitter in a path of the incident light, the polarizing beamsplitter directing light having a first polarization state toward the tooth and directing light from the tooth having a second polarization state along a return path toward a sensor, wherein the second polarization state is orthogonal to the first polarization state; 
 (c) a lens positioned in the return path to direct image-bearing light from the tooth toward the sensor for obtaining image data from the portion of the light having the second polarization state; and 
 (d) a long-pass filter in the return path, to attenuate light in the second spectral range and to transmit light in the first spectral range. 
 
     
     
       2. The apparatus of  claim 1  wherein the polarizing beamsplitter is a wire grid polarizing beamsplitter. 
     
     
       3. The apparatus of  claim 1  wherein said light source is comprised of a first light source having a first spectral range and a second light source having a second spectral range. 
     
     
       4. The apparatus of  claim 3  wherein the light source further comprises a third light and a fourth light, wherein both the third and fourth lights direct a beam toward a point that corresponds with the focus of the lens. 
     
     
       5. The apparatus according to  claim 4  further comprising control logic that automatically detects overlap of light from the third and fourth lights as focus and initiates capture of image data at the sensor. 
     
     
       6. The apparatus of  claim 3  further comprising a band pass filter in the path of the second light source. 
     
     
       7. The apparatus of  claim 1  wherein the lens is telecentric in object space. 
     
     
       8. The apparatus of  claim 1  wherein the sensor is a complementary metal oxide semiconductor (CMOS) sensor. 
     
     
       9. The apparatus of  claim 1  wherein the sensor is a charged couple device (CCD) sensor. 
     
     
       10. The apparatus of  claim 1  wherein the light source is taken from the group consisting of an LED, an incandescent bulb, a super luminescent diode, a diode-pumped solid-state crystal source, and a diode-pumped rare earth-doped fiber source. 
     
     
       11. The apparatus of  claim 1  further comprising an analyzer in the return path. 
     
     
       12. The apparatus of  claim 1  wherein the first spectral range is between about 400 nm and 700 nm. 
     
     
       13. The apparatus of  claim 1  further comprising:
 (e) a display coupled to the sensor for presenting the image data obtained therefrom. 
 
     
     
       14. The apparatus of  claim 1  further comprising:
 (e) an interferometer coupled along the optical path for obtaining an image of a portion of the tooth using optical coherence tomography. 
 
     
     
       15. The apparatus of  claim 1  wherein the second spectral range is between about 300 nm and 500 nm. 
     
     
       16. The apparatus according to  claim 1  further comprising an outlet for directing a pressurized gas toward the tooth. 
     
     
       17. The apparatus according to  claim 1  further comprising a switch enabling an operator to enable either the light in the second spectral range or the light in the first spectral range. 
     
     
       18. The apparatus according to  claim 1  further comprising a second lens for imaging an intermediate image formed by the first lens onto the sensor. 
     
     
       19. An apparatus for imaging a tooth comprising:
 (a) a handle portion for handling and positioning by an operator; 
 (b) a probe portion, separable from the handle portion, for placement in the proximity of the tooth; 
 (c) an optical subsystem housed within the handle and probe portions comprising:
 (i) at least one light source providing incident light having a first spectral range for obtaining a reflectance image on the tooth and a second spectral range for exciting a fluorescence image of the tooth; 
 (ii) a polarizing beamsplitter in a path of the incident light, the polarizing beamsplitter directing light having a first polarization state toward the tooth and directing light from the tooth having a second polarization state along a return path toward a sensor, wherein the second polarization state is orthogonal to the first polarization state; 
 (iii) a lens positioned in the return path to direct image-bearing light from the tooth toward the sensor for obtaining image data from the portion of the light having the second polarization state; and 
 (iv) a long-pass filter in the return path, to attenuate light in the second spectral range and to transmit light in the first spectral range. 
 
 
     
     
       20. The apparatus according to  claim 19  wherein the handle portion further comprises an operator control for initiating operation to obtain an image. 
     
     
       21. The apparatus according to  claim 19  further comprising a wireless interface for sending image data to a communicating device. 
     
     
       22. The apparatus according to  claim 19  further comprising a display for operator viewing of the image data obtained. 
     
     
       23. The apparatus according to  claim 22  wherein the display is taken from the group consisting of a liquid crystal (LC) display and an organic light emitting diode (OLED) display. 
     
     
       24. The apparatus according to  claim 19  further comprising an outlet for directing a pressurized gas toward the tooth. 
     
     
       25. The apparatus according to  claim 19  wherein the probe portion is disposable. 
     
     
       26. The apparatus according to  claim 19  further comprising at least one folding mirror in the optical path. 
     
     
       27. The apparatus according to  claim 26  wherein the at least one folding mirror is treated to reduce fogging effects. 
     
     
       28. The apparatus according to  claim 26  wherein the probe is in communication with a display and wherein the at least one folding mirror cooperates with other components along the optical path to track the tooth surface during movement of the probe. 
     
     
       29. The apparatus according to  claim 19  wherein the probe portion comprises a reflective inner surface.